There are many methods available for locking a previously torqued fastener in place and, thereafter, for indicating whether the fastener has been tampered with or come loose. One common method is to lockwire the fastener; but, lockwiring requires a hole in the fastener as well as in the adjacent structure for the lockwire. The use of a castellated nut and cotter pin also accomplishes this dual function. But, here again, a special nut, a hole through the fastener and, of course, a cotter pin are required. Furthermore, cotter pins are not usable on fluid couplings.
When self-locking fasteners are used, an indicator in the form of a dab of paint across the fastener and adjacent structure is used. Tampering or self-loosening is easy to spot because the paint will be broken at the line between the fastener and the adjacent structure, typically between the nut and washer or bolt head and washer. Unfortunately, most paints are made from organic compounds such as polyurethanes or epoxies. These cannot be used in oxygen-rich environments because a spark will easily ignite and burst them into flames. These paints also do not have the strength to act as a "clock".
Applicant has previously tested numerous commercially available ceramic cements but none have proven adequate. Only one ceramic material has proven usable (SERMETAL), but it becomes brittle and separates from plumbing fittings upon aging. This material has also proved to be difficult to use. Additionally, Applicant has developed a compound which is disclosed in co-pending Patent Application Ser. No. 812,500, "A Locking Compound for Locking Fasteners in Place", which solved the problems outlined above. However, it would be desirable to have a compound with increased pot life and decreased cure times.
Thus, it is a primary object of the present invention to provide a fastener locking compound which provides a visual indication that the fastener has remained properly torqued.
It is another primary object of the subject invention to provide a fastener locking compound which is usable in an oxygen-rich environment.
It is a further primary object of the subject invention to provide a fastener locking compound that provides good adhesion while not deteriorating with age.
It is still a further object of the subject invention to provide a fastener locking compound that is easy to prepare, has improved pot life and cure time, and is easy to apply.